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US6033593A - BALUN transformer core material, BALUN transformer core and BALUN transformer - Google Patents

BALUN transformer core material, BALUN transformer core and BALUN transformer Download PDF

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Publication number
US6033593A
US6033593A US09/094,468 US9446898A US6033593A US 6033593 A US6033593 A US 6033593A US 9446898 A US9446898 A US 9446898A US 6033593 A US6033593 A US 6033593A
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United States
Prior art keywords
balun transformer
transformer core
balun
core material
hexagonal system
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
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US09/094,468
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English (en)
Inventor
Masahiro Onizuka
Kouki Sato
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TDK Corp
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TDK Corp
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Priority to US09/480,160 priority Critical patent/US6217790B1/en
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Publication of US6033593A publication Critical patent/US6033593A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
    • H01F1/34—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials non-metallic substances, e.g. ferrites
    • H01F1/342—Oxides
    • H01F1/344—Ferrites, e.g. having a cubic spinel structure (X2+O)(Y23+O3), e.g. magnetite Fe3O4
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/26—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on ferrites
    • C04B35/2608—Compositions containing one or more ferrites of the group comprising manganese, zinc, nickel, copper or cobalt and one or more ferrites of the group comprising rare earth metals, alkali metals, alkaline earth metals or lead
    • C04B35/2633—Compositions containing one or more ferrites of the group comprising manganese, zinc, nickel, copper or cobalt and one or more ferrites of the group comprising rare earth metals, alkali metals, alkaline earth metals or lead containing barium, strontium or calcium

Definitions

  • the present invention relates to a BALUN transformer core material, a BALUN transformer core which is obtained by pressing and sintering the BALUN transformer core material, and a BALUN transformer which can be operated in a frequency band of 300 MHz or more.
  • the BALUN transformer (Balance to Unbalance transformer: hereinafter abbreviated as BALUN) is a conversion component for smoothly connecting an unbalance circuit and a balance circuit, and used for various electronic apparatus, e.g., an antenna in a communication circuit and the like. Additionally, since the electronic apparatus have been made compact and operated at a high frequency in recent years, an essential countermeasure needs to be taken on constituent components of the electronic apparatus.
  • BALUN transformer is not an exception.
  • the BALUN transformer usually has a structure in which a conductor wire constituted of a metal is wound double around a toroidal or solenoid BALUN transformer core to form a winding (bifilar winding).
  • a BALUN transformer core which is obtained by pressing and sintering a BALUN transformer core material having a high magnetic permeability, e.g., a spinel Ni--Cu--Zn ferrite as an oxide magnetic material.
  • the spinel Ni--Cu--Zn ferrite has a relatively high magnetic permeability and specific resistance, and is not only used as the BALUN transformer core material but also frequently used in a high-frequency coil or other various electronic components.
  • the magnetic permeability of the spinel ferrite including the Ni--Cu--Zn ferrite has a frequency property.
  • the magnetic permeability is reduced in a band of frequencies higher than frequencies at which ferrite starts resonance.
  • Sufficient properties of the BALUN transformer cannot be obtained.
  • the BALUN transformer operable at a high frequency can be obtained.
  • the ferrite has a logic of "Snake's limiting line". Therefore, it is impossible to raise the frequency at which the resonance starts up to a high-frequency band exceeding the limitation.
  • a BALUN transformer cannot be realized which provides an excellent property in the high-frequency band.
  • An object of the present invention is to provide a BALUN transformer core material and a BALUN transformer core which can realize a high-property BALUN transformer which can be operated in a high-frequency band of 300 MHz or more and to provide a BALUN transformer which can be operated in a high-frequency band of 300 MHz or more.
  • the present invention provides a BALUN transformer core material which contains a Z-type hexagonal system ferrite. Since the Z-type hexagonal system ferrite contained in the BALUN transformer core material has an in-plane anisotropy and a high magnetic permeability and a resonance frequency is in excess of the Snake's limiting line, the frequency properties of the magnetic permeability are extremely good.
  • the BALUN transformer core of the present invention is constituted of a sintered material of a ferrite obtained by pressing and sintering the BALUN transformer core material which contains the Z-type hexagonal system ferrite.
  • the BALUN transformer core has a high initial magnetic permeability and specific resistance.
  • the BALUN transformer of the present invention is obtained by applying a winding to the BALUN transformer core having the high magnetic permeability constituted of a sintered material of the ferrite obtained by pressing and sintering the BALUN transformer core material containing the Z-type hexagonal system ferrite.
  • the BALUN transformer is provided with superior properties which are not poorer as compared with the BALUN transformer constituted of a conventional spinel ferrite, and it can also be used in a high-frequency band of 300 MHz or more at which the properties of the conventional BALUN transformer are deteriorated.
  • the compact BALUN transformer with high properties have opened up possibilities of making chips.
  • FIG. 1 is a plan view showing an example of a BALUN transformer according to the present invention.
  • FIG. 2 is a plan view showing another example of the BALUN transformer according to the present invention.
  • FIG. 3 is a perspective view showing another example of the BALUN transformer according to the present invention.
  • FIG. 4 is a perspective view showing a configuration of a BALUN transformer core in an embodiment.
  • FIG. 5 is a circuit diagram showing a measurement circuit of an insertion loss in the embodiment.
  • FIG. 6 is a graph showing measurement results of the insertion loss of the BALUN transformer in the embodiment.
  • the BALUN transformer core material of the present invention is characterized by containing a Z-type hexagonal system ferrite.
  • the three-component hexagonal system ferrite of Fe 2 O 3 --BaO--Mo (wherein M is at least one selected from divalent metal atoms such as Co, Ni, Zn, Mg, Mn, Fe, Cu and Sr) includes an M-type, an X-type, a Y-type and a W-type in addition to the Z-type, and these types are generically called a forroxplana.
  • the Z-type hexagonal system ferrite which can be used in the present invention preferably contains Fe, Ba and Co as constitutional metal atoms, and in this case, the ratio of the constitutional components Fe 2 O 3 , BaO and CoO can be decided in the following range.
  • the Z-type hexagonal system ferrite which can be used in the present invention preferably contains Sr as an additional constitutional metal atom, has an insertion loss of -5 dB or more in a frequency band of 300 MHz to 1.9 GHz, and in this case, the ratio of the constitutional components Fe 2 O 3 , BaO, CoO and SrO can be decided in the following range.
  • the structure of the above-mentioned Z-type hexagonal system ferrite can be confirmed by an X-ray diffraction (XRD).
  • the content of the Z-type hexagonal system ferrite in the BALUN transformer core material is in the range of 60 to 100% by weight, and if the content of the Z-type hexagonal system ferrite is less than 60% by weight, the magnetic permeability inconveniently decreases in a high-frequency band.
  • the BALUN transformer core material of the present invention may contain one or more of PbO, SiO 2 and the like in an amount of 0.01 to 10% by weight, and it is particularly preferred to contain Pb and Si.
  • This BALUN transformer has an insertion loss of -5dB or more in a frequency band of 200 MHz to 1.2 GHz.
  • PbO, SiO 2 and the like may be added at the time of the constitutional components of the Z-type hexagonal system ferrite are blended, or after the constitutional components of the Z-type hexagonal system ferrite have been blended, pre-sintered and then ground, PbO and SiO 2 may be added.
  • PbO and SiO 2 may be added.
  • the same effect can be obtained.
  • the BALUN transformer core of the present invention is obtained by mixing the BALUN transformer core material (which is preliminarily sintered and then ground) of the present invention with the binder, pressing the mixture into a predetermined configuration, and then really sintering the thus pressed material at a high temperature.
  • the binder an organic compound such as polyvinyl alcohol (PVA) or polyethylene glycol (PEG), or water can be used. Furthermore, a mixture of PVA and PEG, or a mixture of two or more of PVAs having different polymerization degrees can be used.
  • the mixing proportion of the binder and the BALUN transformer core material can be set in such a manner that 1 to 15 parts by weight of binder is mixed with 100 parts by weight of the BALUN transformer core material.
  • the binder may contain 0 to 2.0% by weight of one type or more types of dispersing agent such as a carboxylic acid dispersant, a sulfonic acid dispersant and the like.
  • the configuration of the BALUN transformer core according to the present invention may be the same as the configuration of the conventional BALUN transformer core such as a toroidal configuration, a solenoid configuration, a configuration of a pair of glasses or the like.
  • the magnetic permeability (about 6 to 15) and the specific resistance (10 6 ⁇ cm or more) of the BALUN transformer core of the present invention are about the same degree as that of the conventional BALUN transformer core in which the spinel Ni--Cu--Zn ferrite is used, and the BALUN transformer core of the present invention has excellent characteristics as the BALUN transformer core.
  • the specific resistance of the BALUN transformer core is low (10 4 ⁇ cm or less), the insulation between the core and the winding, and between core electrodes cannot be kept unfavorably.
  • FIGS. 1 to 3 Examples of the BALUN transformer according to the present invention are shown in FIGS. 1 to 3.
  • a BALUN transformer 1 of the present invention shown in FIG. 1 is constituted by winding a paired wire 3 around a toroidal BALUN transformer core 2 and thus applying a winding.
  • a BALUN transformer 11 of the present invention shown in FIG. 2 is constituted by winding a coaxial wire 13 around a toroidal BALUN transformer core 12 and thus applying a winding.
  • a BALUN transformer 21 of the present invention shown in FIG. 3 is constituted by applying a coaxial wire 23 to a BALUN transformer core 22 configured like a pair of glasses which is provided with through holes 22a and 22b.
  • each BALUN transformer core material contained a Z-type hexagonal system ferrite.
  • a comparative sample was prepared.
  • NiO, CuO, ZnO and Fe 2 O 3 were weighed so as to be 42NiO•4CuO•6ZnO•48Fe 2 O 3 in terms of an oxide composition (mol %).
  • a preliminary calcination was performed at a temperature of 900° C. in an air atmosphere for two hours.
  • a wet-grinding was performed in the ball mill to form a BALUN transformer core material constituted of a spinel Ni--Cu--Zn ferrite.
  • a paste was prepared in the same manner as aforementioned.
  • a toroidal configuration, an E-shaped BALUN transformer core (a comparative sample) and a disk-shaped sample (a comparative sample) were prepared.
  • a winding is applied to a BALUN transformer core having a toroidal configuration by winding a pair line thereon, and the initial magnetic permeability is then measured in accordance with an inductance method prescribed in JIS C2561 by the use of an LCR meter (HP4275, manufactured by Furet Paccard Co., Ltd.).
  • An In--Ga electrode is placed on an end surface of a disc-shaped sample.
  • the insulation resistance is measured with an insulation testing set (SUPER MEG OHM METER SM-5E manufactured by Toa Denpa Kogyo Kabushiki Kaisha).
  • the specific resistance is calculated from an outside dimension of the sample.
  • the BALUN transformer cores (samples 1-7) of the present invention have initial magnetic permeabilities of 6 to 15 and specific resistances of 10 6 ⁇ cm or more, which are not poorer as compared with the comparative sample in which a spinel Ni--Cu--Zn ferrite is used.
  • the insertion loss was measured in a measurement circuit shown in FIG. 5 by using a network analyzer (HP-8753 manufactured by Furet Paccard Co., Ltd.). The results are shown in FIG. 6. Additionally, in the measurement circuit shown in FIG. 5, to enhance a measurement precision, two BALUN transformers prepared as aforementioned are connected in series. Therefore, the insertion loss shown in FIG. 6 is a double value. Therefore, when the insertion loss is -3 dB in FIG. 6, the insertion loss of one BALUN transformer is -1.5 dB. The closer to 0 dB the insertion loss is, the more superior the property of the BALUN transformer becomes.
  • a frequency band in which an insertion loss of -5 dB or more can be obtained is 200 MHz to 1.2 GHz in the sample 1 of the BALUN transformer of the present invention, and 300 MHz to 1.9 GHz in the sample 5 of the BALUN transformer of the present invention.
  • a frequency band in which an insertion loss of -2 dB or more can be obtained is 400 MHz to 870 MHz in the sample 1 of the BALUN transformer of the present invention, and 590 MHz to 1.3 GHz in the sample 5 of the BALUN transformer of the present invention.
  • the BALUN transformers of the present invention have remarkably small insertion losses in the high-frequency band as compared with the BALUN transformer of the comparative sample. It has been confirmed that the BALUN transformer of the present invention can be operated in a high-frequency band of 300 MHz or more.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Dispersion Chemistry (AREA)
  • Power Engineering (AREA)
  • Soft Magnetic Materials (AREA)
  • Coils Or Transformers For Communication (AREA)
  • Magnetic Ceramics (AREA)
US09/094,468 1997-06-17 1998-06-10 BALUN transformer core material, BALUN transformer core and BALUN transformer Expired - Fee Related US6033593A (en)

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Application Number Priority Date Filing Date Title
US09/480,160 US6217790B1 (en) 1997-06-17 2000-01-10 BALUN transformer core material, BALUN transformer core and BALUN transformer

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP9-176323 1997-06-17
JP9176323A JPH118112A (ja) 1997-06-17 1997-06-17 バルントランス用コア材料、バルントランス用コアおよびバルントランス

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6217790B1 (en) * 1997-06-17 2001-04-17 Tdk Corporation BALUN transformer core material, BALUN transformer core and BALUN transformer
US6379579B1 (en) * 1999-03-09 2002-04-30 Tdk Corporation Method for the preparation of soft magnetic ferrite powder and method for the production of laminated chip inductor
EP1249847A3 (en) * 2001-04-09 2003-01-02 Toda Kogyo Corporation Soft-magnetic hexagonal ferrite composite particles, and green sheet using the same and soft-magnetic hexagonal ferrite sintered ceramics.
US20090295526A1 (en) * 2006-03-29 2009-12-03 Hideto Mikami Coil Component and Its Manufacturing Method
US20130169375A1 (en) * 2011-07-01 2013-07-04 Ralph Oppelt Broadband balun
US10209328B2 (en) 2016-05-27 2019-02-19 General Electric Company Systems and methods for common mode traps in MRI systems
US10379181B2 (en) * 2016-05-27 2019-08-13 General Electric Company Systems and methods for common mode traps in MRI systems

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3551863B2 (ja) * 1999-10-27 2004-08-11 株式会社村田製作所 複合磁性材料およびインダクタ素子
JP4069284B2 (ja) * 2001-02-23 2008-04-02 Ｔｄｋ株式会社 磁性フェライト材料および積層型フェライト部品
JP3726017B2 (ja) * 2000-10-31 2005-12-14 Ｔｄｋ株式会社 磁性材料およびインダクタ
US6750752B2 (en) 2002-11-05 2004-06-15 Werlatone, Inc. High power wideband balun and power combiner/divider incorporating such a balun
KR100501200B1 (ko) * 2003-12-03 2005-07-18 삼성전기주식회사 바룬트랜스
US7936171B2 (en) * 2007-11-21 2011-05-03 Brandeis University Baluns, a fine balance and impedance adjustment module, a multi-layer transmission line, and transmission line NMR probes using same
CN106920655A (zh) * 2017-04-18 2017-07-04 重庆祥龙电气股份有限公司 一种交错式防雷变压器

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US3100852A (en) * 1956-07-28 1963-08-13 Philips Corp Variable reluctance magnetic circuit
JPS59216151A (ja) * 1983-05-24 1984-12-06 Hitachi Metals Ltd 電子写真用フエライトキヤリアの現像方法
JPS61208913A (ja) * 1985-03-13 1986-09-17 Matsushita Electric Ind Co Ltd バランコイル
JPS6290911A (ja) * 1985-10-17 1987-04-25 Matsushita Electric Ind Co Ltd バランコイル
JPH03161910A (ja) * 1989-11-21 1991-07-11 Tdk Corp インピーダンス素子
JPH09110432A (ja) * 1995-10-12 1997-04-28 Tdk Corp Ｚ型六方晶系酸化物磁性材料

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US5593612A (en) * 1990-11-30 1997-01-14 The United States Of America As Represented By The Secretary Of The Navy U, W, X, Y and Z-type ferrites
US5954992A (en) * 1996-07-26 1999-09-21 Tdk Corporation Hexagonal Z type magnetic oxide sintered material, method for making and impedance device
JPH118112A (ja) * 1997-06-17 1999-01-12 Tdk Corp バルントランス用コア材料、バルントランス用コアおよびバルントランス

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Publication number Priority date Publication date Assignee Title
US2946752A (en) * 1955-08-10 1960-07-26 Philips Corp Ferromagnetic material
US3100852A (en) * 1956-07-28 1963-08-13 Philips Corp Variable reluctance magnetic circuit
JPS59216151A (ja) * 1983-05-24 1984-12-06 Hitachi Metals Ltd 電子写真用フエライトキヤリアの現像方法
JPS61208913A (ja) * 1985-03-13 1986-09-17 Matsushita Electric Ind Co Ltd バランコイル
JPS6290911A (ja) * 1985-10-17 1987-04-25 Matsushita Electric Ind Co Ltd バランコイル
JPH03161910A (ja) * 1989-11-21 1991-07-11 Tdk Corp インピーダンス素子
JPH09110432A (ja) * 1995-10-12 1997-04-28 Tdk Corp Ｚ型六方晶系酸化物磁性材料

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6217790B1 (en) * 1997-06-17 2001-04-17 Tdk Corporation BALUN transformer core material, BALUN transformer core and BALUN transformer
US6379579B1 (en) * 1999-03-09 2002-04-30 Tdk Corporation Method for the preparation of soft magnetic ferrite powder and method for the production of laminated chip inductor
EP1249847A3 (en) * 2001-04-09 2003-01-02 Toda Kogyo Corporation Soft-magnetic hexagonal ferrite composite particles, and green sheet using the same and soft-magnetic hexagonal ferrite sintered ceramics.
US6623879B2 (en) 2001-04-09 2003-09-23 Toda Kogyo Corporation Soft-magnetic hexagonal ferrite composite particles, and green sheet using the same and soft-magnetic hexagonal ferrite sintered ceramics
KR100794066B1 (ko) * 2001-04-09 2008-01-10 토다 고교 가부시끼가이샤 연자성 육방정 페라이트 복합 입자, 및 그를 이용한 그린시트 및 연자성 육방정 페라이트 소결 세라믹
US20090295526A1 (en) * 2006-03-29 2009-12-03 Hideto Mikami Coil Component and Its Manufacturing Method
US20130169375A1 (en) * 2011-07-01 2013-07-04 Ralph Oppelt Broadband balun
US9154106B2 (en) * 2011-07-01 2015-10-06 Siemens Aktiengesellschaft Broadband balun
US10209328B2 (en) 2016-05-27 2019-02-19 General Electric Company Systems and methods for common mode traps in MRI systems
US10379181B2 (en) * 2016-05-27 2019-08-13 General Electric Company Systems and methods for common mode traps in MRI systems

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JPH118112A (ja) 1999-01-12
US6217790B1 (en) 2001-04-17

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